VERITAS Results on Galactic Sources in Cygnus (UCLA) for the VERITAS Collaboration ICRC 2013 (Rio de Janeiro) July 2013
OUTLINE VHE γ-rays as probes of Galactic CR origin The VERITAS Observatory The Cygnus region and VERITAS Sky Survey New results on: VER J2019+407 (γ-cygni) TeV J2032+4130 (first Un-ID TeV source) Cisne Region (MGRO J2019+37) (Cygnus X-3 3, MGRO 1908+06) Summary
Rich Variety of VHE Sources CR s Pulsars Pulsar Wind Nebulae Binary systems Supernova Remnants NS dynamo Winds Star Forming Regions Accretion-powered jets, Colliding winds, or? Un-Identifieds Shocks Fermi mechanism Origin of CRs? OB Assoc., WR stars, molecular clouds, etc.???
VERITAS U.S. Adler Planetarium UCLA Argonne Nat. Lab UCSC Barnard College U. of Chicago DePauw Univ. U. of Delaware Grinnell College U. of Iowa Iowa St. Univ. U, of Minnesota Purdue Univ. U. of Utah SAO Washington U. Canada McGill Univ. Ireland Non-Affilated Members Cork University. N.U.I Galway Galway-Mayo Inst. Univ. College Dublin Anderson Univ. DESY/Potsdam Penn State Call Poly Georgia Tech De Pauw Grinnell June 2013 (Berlin) Support from: Energy Range: 85 GeV 30 TV TeV U.S. DOE U.S. NSF Energy Resolution: 15-25% Smithsonian NSERC (Canada) Angular Resolution: < 0.1 deg (68%) STFC (UK) Sensitivity: < 25 hr (1% Crab) SFI (Ireland) (Summer 2012) VERITAS Upgrade High QE PMTs New Tel Trigger
VERITAS Cygnus Sky Survey HE/VHE Sky Surveys: HEGRA: North, ~25% Crab HESS: South, ~3% Crab, extended Milagro (01-07): North, ~35% Crab at E > 10 TeV EGRET/Fermi-LAT: GeV band Cygnus Region: Rich in star forming activity Many potential VHE accelerators VERITAS Sky Survey (07-09): N. Hemisphere Cygnus arm. 115h + 55h follow-up; done before improvements to sensitivity. ~3% Crab (99%) for E > 200 GeV. Note bright MGRO J2019+37 VERITAS Survey VER J2019+407 HESS Survey
VER J2019+407 (γ-cygni) VERITAS Sky Survey (2007-09) (plus follow-up on VER J2019+407) E. Aliu et al., ApJ 770, 93 (2013) VERITAS Follow-up (2009) VER J2019+407 Fermi-LAT Cocoon TeV J2032+4130 VERITAS extent (black circle) Discovery of VER J2019+407 21.4 hr follow-up observations, 7.5σ post-trials Extension of 0.23 ± 003 0.03 +0.04 stat ( -0.02)) sys deg Source at NW rim of G78.2+2.1 (γ-cygni) in region of enhanced radio emission Pulsar and Fermi-LAT emission displaced from VERITAS source PSR J2021+4026 (yellow star) CGPS 1420 MHz (white contours) Fermi-LAT >10 GeV emission (yellow circle,center at inverted triangle)
VER J2019+407 (γ-cygni) VERITAS Spectrum X-ray & VERITAS E. Aliu et al., ApJ 770, 93 (2013) ASCA 1-3 kev, enhanced emission, fitted by Raymond- Smith model No evidence for non-thermal X-ray emission PSR J2021+4026 (star) Single power-law form Γ = 237 2.37 ± 014 0.14 stat ± 0.20 020 sys 3.7% Crab E>320 GeV Interpretation PWN? SNR? Pulsar offset Shock interaction of ejecta with dense HI shell Required density (p) ~1.0-5.5 55cm -3 (similar to/less than inferred from optical)
TeV J2032+4130 TeV J2032+4130 First un-identified TeV source (HEGRA) Confirmed by MAGIC, Whipple source extension of ~ 6 arc-mins MGRO J2031+41: bright emission over a much larger area No clear picture of its nature PSR J2032+4127 (blue star) E. Aliu et al. (in preparation, 2013) Wobble positions (red) VERITAS Observations Cyg Detected in the Sky Survey (2007-09) Follow-up of 48.2 hr, 8.7σ significance Position consistent t with previous ones Asymmetric extension major axis: 0.16 ± 0.02 degs (NW) minor axis: 0.066 066 ± 0.009009 degs No evidence for E dependent morphology Hard spectrum, single power-law form Γ =205± 2.05 016 0.16 stat ± 021 0.21 sys N 0 = 9.3 ± 1.6 stat ±2.2 sys x 10-13 TeV -1 cm -2 s -1 Cyg X-3 (black triangle)
TeV J2032+4130 VER J2032+415 E. Aliu et al. (in preparation, 2013) VHE γ-rays (VERITAS) 1.4 GHz (CGPS) MWL Picture Fermi-LAT pulsar (blind search) PSR J2032+4127, P=142 ms 0.25o relatively old and weak. No un-pulsed Fermi-LAT emission seen (our analysis). MGRO source has softer spectrum, but integrates over larger size 24 μm (Spitzer MIPS) 8 μm (Spitzer GLIMPSE) Interpretation: PWN TeV source is in void of generally bright emission at longer wavelengths. No SNR shell detected, but VHE emission consistent with pulsar wind powered by Fermi-LAT pulsar. Characteristics of PSR J2032+4127 are consistent s with TeV PWN population. o
TeV J2032+4130 E. Aliu et al. (in preparation, p 2013) MSX 8μm survey VERITAS = white line Milagro = Black line Characteristics of PSR J2032+4127
Cisne Region (MGRO J2019+37) MGRO J2019+37 One of three bright sources detected by Milagro, broad (1.2 o x 0.7 o ), not resolved Excellent angular resolution of VERITAS allows for a sharper image VERITAS Observations (2010) 71 hr complex sky map, with multiple sources VER J2016+371: point source, consistent with CTB 87 VER J2019+368: extended emission, possibly multiple sources covering ~1 deg MGRO E>20 TeV white Fermi 2FGL green circles VER J2019+368 VER J2016+371 E. Aliu et al. (in preparation, 2013) Integration θ 2 < 0.008 deg 2 Integration θ 2 < 0.055 deg 2
Spectra and CTB 87 VERITAS Spectra CTB 87 Region VERITAS: 3,4,5σ contours E. Aliu et al. (in preparation, 2013) Γ = 1.75 ± 0.08stat ±0.3sys CGPS Γ = 2.3 ± 0.3stat ±0.3sys Chandra VER J2019+368 VER J2016+371 (CTB 87) is weaker & softer VER J2019+368 is compatible with MGRO VER J2016+371 point source emission at location of CTB 87. X-ray/radio suggest PWN, no pulsar yet detected 2FGL source probably not related
Sharper View of MGRO J2019+37 CGPS 408 MHz XMM-Newton (0.5-8 kev) VERITAS > 600 GeV HII region E. Aliu et al. (in preparation, 2013) VHE emission appears to follow ridge of diffuse radio emission Signif. fraction (~50%) VHE could derive from PWN powered by PSR J2021+3651 Remainder of VHE is still unattributed (unknown nebula? winds in HII region? )
The VERITAS view of Cygnus VER J2019+407 (SNR shock) VER J2016+371 (Pulsar Wind) VER J2019+368 (Unknown) In Gal plane, not in Cygnus VER J2032+415 (Pulsar wind) All five papers to be published In 2013 MGRO 1908+06 (stay tuned) Cyg X-3 (Not seen at TeV)
Summary Cygnus is a rich, complex region in VHE γ-rays. VERITAS has taken ~250 hr of data in Cygnus over 2007-2012, leading to: discovery of new sources a sharper view, compared to previous surveys 2013 Results: VER J2019+407: (SNR interaction) TeV J2032+4130: (PWN) Cisne: CTB 87 (PWN) MGRO J2019+37 (complex, not understood) Cyg X-3: not yet detected Extending knowledge of TeV Galactic sources origin of CR s